Electric coupling having molded end



Jan. 24, 1956 J. E. G. CHAPMAN 2,732,421

ELECTRIC COUPLING HAVING MOLDED END SEAL FOR CONDUCTOR Filed June '7, 1950 Inventor Joseph [award Geo/fray Cfrapm an Attorneys United States Patent ELECTRIC COUPLING HAVING MOLDED END SEAL FOR CONDUCTOR Joseph Edward Geoffrey Chapman, Workington, Cumberland, England, assignor to British Insulated Callenders Cables Limited, London, England, a British company Application June 7, 1950, Serial No. 166,753

Claims priority, application Great Britain July 8, 1949 3 Claims. (Cl. 174-76) This invention relates to electrical apparatus of the kind in which a conducting member is supported within a metal casing by insulating material which is injected into the casing under pressure in a molten or plastic (hereinafter referred to for convenience as molten) state, and which then sets. To ensure that the casing is completely filled with the molten insulating material a spew-hole, or a number of spew-holes, is provided. The flowing out of the insulating material through the spew-hole or spew-holes indicates that the metal casing is filled. There is a risk of moisture being drawn into the interior of the casing through a spew-hole during service and the object of the present invention is to provide a construction whereby the drawing in of moisture is prevented. This is effected, according to the invention, by making the spew-hole, at an outer part, of greater cross-sectional area than at an inner part, so that shrinkage of the insulating material within the casing causes the insulating material in the spew-hole to be drawn tightly against the wall of the spew-hole to form a seal.

The invention will be described further with the aid of the accompanying drawings, wherein Figure 1 is a longitudinal view in elevation and partly in section of an electric cable coupling member embodying one form of construction of spew-hole and Figure 2 is a fragmentary view in elevation also partly in section, illustrating a modified form of spew-hole.

In Figure 1 there is shown a coupling member, indicated generally by the reference numeral 1, attached to one end of an electric cable 2 provided with conductors 3. The coupling member forms part of a coupling device of the plug and socket type and is shown provided with pins 4 for insertion into sockets carried by the other part of the coupling device, not shown.

Pins 4 are provided with terminal members 5 to which are attached, in any convenient manner, the conductors 3. The latter and the terminal members 5 are disposed within a metal casing 6, and are supported therein by insulating material 7.

The metal casing 6 is provided with a spew-hole 8 which has an outer cylindrical portion 9 and an adjacent inner cylindrical portion 10, the portion 9 being of greater cross-sectional area than the inner portion 10, the two portions thus forming between them an annular step 11. The step slopes in a. direction towards the interior of the casing 6 from its outer part towards its inner part. It will be seen from Figure 1 that the shape of the spew-hole is such that when filled with molten insulating material which is allowed to set, the solid material will be so shaped that it has a head and a shank. The head is indicated by the reference numeral 13 and the shank by the reference numeral 14.

The insulating material in a molten state is injected under pressure into the metal casing 6 in any suitable manner, the flowing out of the material through the spew-hole 8 indicating that the casing is full. Under these conditions there will, of course, be a body of insu- 2,732,421 Patented Jan. 24, 1956 ice lating material within the metal casing and also a body of such material within the spew-hole, the one body being integral with the other.

After the casing and the spew-hole have been filled with the insulating material 7, the latter sets and it also shrinks with the result that the head 13 is drawn tightly against the step 11 to form a seal which will prevent the passage of moisture past it into the interior of the metal casing 6.

The sealing effect described above is also obtained by the construction of spew-hole illustrated in Figure 2, where the spew-hole 8 is shown as having a continuous taper from its outer end to its inner end, the spew-hole having the shape of a truncated cone. In the construction shown in Figure 2, shrinkage of the insulating material within the metal casing draws the insulating material within the spew-hole towards the interior of the casing to effect, by a wedging action, the sealing of the spewhole to prevent the entry of moisture past the seal into the interior of the metal casing 6.

V v-"here necessary, the wall of the metal casing 6 may be thickened up, as shown in the figures, to ensure an ample depth of the spew-hole.

From the figures of the drawings it will be seen that the insulating material within the metal casing 6 terminates at its inner end flush with the corresponding ends of the terminal members 5 so as to leave a free space into which the pins 4 project and to provide for the entry of the latter into corresponding socket members of the other part of the coupling device. The metal casing 6 has at its inner end an externally threaded flange 12 whereby the other part of the coupling device may be attached to the coupling member 1.

It will be understood that the pins 4, or some of them, may be replaced by sockets, and that any number of pins and/or sockets may be used according to requirements. Furthermore, the metal casing 6 may be provided with one or more spew-holes as may be required.

The invention is not limited thereto, but has been found to be particularly useful in those cases where a length of electric cable is required to be coupled to another length or to some other piece of electrical apparatus and polyethylene is used to support the pins and/ or sockets of the coupling member and the ends of the cable conductors connected thereto, the molten polyethylene being forced under pressure into the interior of the metal casing and then being allowed to set.

What I claim as my invention is:

1. Electrical apparatus comprising a metal casing having a spew-hole, an outer part of which is of greater cross-sectional area than that of an inner part, a mould able insulating material in the casing, a head of insulating material in the outer part of the spew-hole and a shank of insulating material in the inner part thereof, said head and shank forming a single integral body with the insulating material in the casing whereby contraction of the insulating material in the casing draws the head into sealing engagement with the walls of the spew-hole sealing the metal casing against the entry of moisture through the spew-hole, and a conducting member supported by the insulating material in the casing.

2. Electrical apparatus comprising a metal casing having a spew-hole of truncated conical shape in crosssection, the outer part of the spew-hole being of greater cross-sectional area than that of the inner part, a mouldable insulating material in the casing, a head of insulating material in the outer part of the spew-hole and a shank of insulating material in the inner part thereof, said head and shank forming a single integral body with the insulating material in the casing whereby contraction of the insulating material in the casing draws the head into sealing 3 engagement with, the Walls of the spew-hole sealing the metal casing against the entry of moisture through the spew-hole, and a conducting member supported by the insulating material in the casing.

3.. Electrical. apparatus comprising, a metal casing having a spew-hole, an outer part of which is of greater cross-sectional area than that, of an adjacent; inner part, a step being thus; formedbetween the two parts, a mouldable insulating material in the. casing, a head of insulating material. in the outer part. of the spew-hole held. against the step and forming a seal against the entry of moisture through the spew-hole into the casing, a, shank of mouldable insulating material in the adjacent inner part of the spew-hole, connecting the head of, insulating material with the insulating. material in the body to form a single; integral bodywhereby contraction of the insulating material in the; casing draws the head into sealing References Cited in the file of this patent UNITED STATES PATENTS 586,463 Tobey July 13, 1897 727,829 OConnell May 1 2, 1903 1,103,983 Murray July 21, 1914 1,135,376 Hooker Apr. 13, 1915 2,014,288 Naschang Sept. 10, 1935 2,274,823 Candy Mar. 3', 1942 2,305,150 Fearon Dec. 15, 1942 2,371,551 Sehmitt Mar. 13, 1945 2,406,405 Salisbury Aug. 27, 1946 2,590,160 Dixon Mar; 25, 1952 

